As people's living standards improve, their demands for high quality life is increased more and more. The traditional wooden or bamboo chairs are gradually replaced by those with elegant style and multifunctionality. Modern chairs are designed more and more user-friendly chairs, which meet consumers' needs for comfort and convenience. One of the modern chairs has a backrest tilt angle which is adjustable to allow people to sit more comfortably by changing the angle between the seat and the backrest. However, during a backrest turning backward, the turning center and turning radius of the backrest are different from those of the user's body, therefore the user's clothes is pulled up by the friction between the backrest and the user, which results in unpretty wrinkles or even damages of the clothes, or results in exposures of the user's waist which causes embarrassment on some occasions. Thus, the purpose of the present invention is to provide a rotary chair which can avoid the pulling up of a user's clothes when the backrest is turned backward.